Anton N. Lukoyanov

Dialane with a Redox-Active Bis-amido Ligand: Unique Reactivity towards Alkynes

The treatment of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) with one equivalent of AlCl(3) and three equivalents of sodium in toluene at 110 °C produced a stable dialane, (dpp-bian)Al-Al(dpp-bian) (1). The reaction of compound 1 with pyridine gave Lewis-acid-base adduct (dpp-bian)(Py)Al-Al(Py)(dpp-bian) (2). Acetylene and phenylacetylene reacted with compound 1 to give cycloaddition products [dpp-bian(R(1)R(2))]Al-Al[(R(2)R(1))dpp-bian] (3: R(1)=R(2)=CH; 4: R(1)=CH, R(2)=CPh). These addition reactions occur across Al-N-C moieties and result in the formation of new C-C and C-Al bonds. At elevated temperatures, compound 4 rearranges into complex 5, which consists of a radical-anionic dpp-bian ligand and two bridging alken-1,2-diyl moieties, (dpp-bian)Al(HCCPh)(2)Al(dpp-bian). This transformation is accompanied by cleavage of the dpp-bian-ligand-alkyne C-C bond, as well as of the Al-Al bond. In contrast to its analogous gallium complex, compound 1 is reactive towards internal alkynes. In the reaction of compound 1 with PhC≡CMe, besides symmetrical addition product [dpp-bian(R(1)R(2))]Al-Al[(R(2)R(1))dpp-bian] (R(1)=CMe, R(2)=CPh; 6), monoadduct [dpp-bian(R(1)R(2))]Al-Al(dpp-bian) (R(1)=CMe, R(2)=CPh; 7) was also isolated. Complexes 1-7 were characterized by IR, (1)H NMR (1-4), and electronic absorption spectroscopy (3-5); the molecular structures of compounds 1-7 were determined by single-crystal X-ray diffraction.

Reduction of Digallane [(dpp‐bian)GaGa(dpp‐bian)] with Group 1 and 2 Metals

The reduction of digallane [(dpp-bian)Ga-Ga(dpp-bian)] (1) (dpp-bian=1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with lithium and sodium in diethyl ether, or with potassium in THF affords compounds featuring the direct alkali metal-gallium bonds, [(dpp-bian)Ga-Li(Et(2)O)(3)] (2), [(dpp-bian)Ga-Na(Et(2)O)(3)] (3), and [(dpp-bian)Ga-K(thf)(5)] (7), respectively. Crystallization of 3 from DME produces compound [(dpp-bian)Ga-Na(dme)(2)] (4). Dissolution of 3 in THF and subsequent crystallization from diethyl ether gives [(dpp-bian)Ga-Na(thf)(3)(Et(2)O)] (5). Ionic [(dpp-bian)Ga](-)[Na([18]crown-6)(thf)(2)](+) (6a) and [(dpp-bian)Ga](-)[Na(Ph(3)PO)(3)(thf)](+) (6b) were obtained from THF after treatment of 3 with [18]crown-6 and Ph(3)PO, respectively. The reduction of 1 with Group 2 metals in THF affords [(dpp-bian)Ga](2)M(thf)(n) (M=Mg (8), n=3; M=Ca (9), Sr (10), n=4; M=Ba (11), n=5). The molecular structures of 4-7 and 11 have been determined by X-ray crystallography. The Ga-Na bond lengths in 3-5 vary notably depending on the coordination environment of the sodium atom.

New high-spin iron complexes based on bis(imino)acenaphthenes (BIAN): synthesis, structure, and magnetic properties

The reactions of iron diiodide with one and two equivalents of the monopotassium salt of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-BIAN) in diethyl ether gave the complexes [(dpp-BIAN)FeI]2 (1) and (dpp-BIAN)2Fe (2), respectively. The bis-ligand complex (tms-BIAN)2Fe (3) was synthesized by the exchange reaction of the monosodium salt of 1,2-bis(trimethylsilylimino)acenaphthene (tms-BIAN) with iron diiodide. The reaction of FeI2 with tms-BIAN affords the chelate complex (tms-BIAN)FeI2 (4), whereas the reaction of FeBr2·2H2O with tms-BIAN is accompanied by elimination of trimethylsilyl groups to form the tris-ligand acenaphthene-1,2-diimine complex [(H2BIAN)3Fe][FeBr3·THF]2 (5) containing two types of iron ions. Compounds 1–5 were characterized by IR spectroscopy and elemental analysis. The molecular structures of 1–5 were determined by single-crystal X-ray diffraction. For high-spin complexes 1–3, the temperature-dependent magnetic susceptibilities were measured in the range of 4–300 K.

Organometallic Compounds of the Lanthanides 182 (1). Calcium and Neodymium Complexes Containing the dpp-BIAN Ligand System: Synthesis and Molecular Structure of ((dpp-BIAN)CaI(THF) 2 ) 2 and ((dpp-BIAN)NdCl(THF) 2 ) 2

Oxydation of (dpp-BIAN)Ca(THF)4 with 0.5 equiv. of I2 in THF yields [(dpp-BIAN)CaI(THF)2]2 (1). A corresponding neodymium compound [(dpp-BIAN)NdCl(THF)2]2 (2) has been obtained by reaction of (dpp-BIAN)Na2 with NdCl3 in THF. The X-ray single crystal structure analyses show 1 and 2 to be isostructural dimers containing octahedrally coordinated metal atoms bridged by the respective halides. The chelating dpp-BIAN ligand acts as a radical anion in the Ca2+ complex 1 and as a dianion in the Nd3+ complex 2, respectively.

Complexes of gallium(III), antimony(III), titanium(IV), and cobalt(II) with acenaphthenequinonimine

Reactions of (2,6-diisopropylphenylimino)acenaphthenone (dpp-mian) with gallium(III), antimony(III), titanium(IV), and cobalt(II) chlorides in toluene lead to the formation of compounds of the formulas [(dpp-mian)2GaCl2][GaCl4], (dpp-mian)SbCl3, (dpp-mian)TiCl4, and [(dpp-mian)CoCl2]2[CoCl2(EtOH)4], respectively. The complexes were characterized by IR and NMR spectra, their structure was established by X-ray crystallography.

1,3,2-Diazasilols based on 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene

Reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (1, dpp-bian) in the presence of SiCl4 with two equivalents of potassium graphite (KC8) in tetrahydrofuran leads to the formation of compound (dpp-bian)SiCl2 (2), which was also synthesized by the exchange reaction of SiCl4 with the magnesium complex (dpp-bian)Mg(THF)3. An analog of compound 2, the bromo derivative (dpp-bian)SiBr2 (3), was obtained by the reaction of SiBr4 with one equivalent of Na2(dpp-bian) (in situ from Na and dpp-bian) in toluene. The silylene (dpp-bian)Si (4) was synthesized by the reduction of a mixture of dpp-bian and SiCl4 (1: 1) with four equivalents of potassium graphite in tetrahydrofuran. Treatment of compound 4 with diimine 1 gives the derivative (dpp-bian)2Si (5). Compounds 2–5 were characterized by 1H, 13C, and 29Si NMR spectroscopy, as well as by elemental analysis, their molecular structure was established by X-ray diffraction studies.

Gallium Complexes with Acenaphthene-1-Imino-2-one: Synthesis and Reactivity

The reduction of acenaphthene-1-(2,6-diisopropylphenyl)imino-2-one (Dpp-Mian) by gallium in the presence of iodine primarily results in a bis(ligand) paramagnetic derivative [(Dpp-Mian)2GaI] and then to a dimeric diamagnetic complex [(Dpp-Mian)GaI]2, the reaction of which with PhC≡CH gives a cycloaddition product [{Dpp-Mian(HC=CPh)}GaI]2. The new compounds are characterized by IR spectroscopy and 1H NMR spectroscopy. The structures of complexes (Dpp-Mian)2GaI and [{Dpp- Mian(HC=CPh)}GaI]2 are determined by X-ray structure analysis (CIF files CCDC nos. 1571860 and 1571861, respectively). The catalytic activity tests for compounds [(Dpp-Mian)GaI]2 and [{Dpp-Mian(HC=CPh)}GaI]2 are conducted in the reactions of 4-chloroaniline with phenylacetylene and carbodiimide and in the reaction of phenylacetylene with 1-naphthol.

Lanthanum Complexes with a Diimine Ligand in Three Different Redox States

The reduction of 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-Bian) with an excess of La metal in the presence of iodine (dpp-Bian/I2 = 2/1) in tetrahydrofuran (thf) or dimethoxyethane (dme) affords lanthanum(III) complexes of dpp-Bian dianion: deep blue [(dpp-Bian)2-LaI(thf)2]2 (1, 84%) was isolated by crystallization of the product from hexane, while deep green [(dpp-Bian)LaI(dme)2] (2, 93%) precipitated from the reaction mixture in the course of its synthesis. A treatment of complex 1 with 0.5 equiv of I2 in thf leads to the oxidation of the dpp-Bian dianion to the radical anion and results in the complex [(dpp-Bian)1-LaI2(thf)3] (3). Addition of 18-crown-6 to the mixture of 1 and NaCp* (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl) in thf affords ionic complex [(dpp-Bian)2-La(Cp*)I][Na(18-crown-6)(thf)2] (4, 71%). In the absence of crown ether the alkali metal salt-free complex [(dpp-Bian)2-LaCp*(thf)] (5, 67%) was isolated from toluene. Reduction of complex 1 with an excess of potassium produces lanthanum-potassium salt of the dpp-Bian tetra-anion {[(dpp-Bian)4-La(thf)][K(thf)3]}2 (6, 68%). Diamagnetic compounds 1, 2, 4, 5, and 6 were characterized by NMR spectroscopy, while paramagnetic complex 3 was characterized by the electron spin resonance spectroscopy. Molecular structures of 2-6 were established by single-crystal X-ray analysis.